Total Security 2019 blocking NVR functionality

I have a Network Video Recorder with IP cameras attached that uses a web-based interface to view camera feeds, both live and recorded playback.  The video functionality is provided via a NPAPI plugin.

Using both Firefox 52.0.9esr (which still has NPAPI support) and Pale Moon (a Firefox fork that will always have NPAPI), everything works fine without Bitdefender.  Immediately after installing it, the live view functionality stops working.  Playback still works.

This is true on three machines thus far, one running Windows 8.1, two running Windows 10.  Cameras working immediately before Bitdefender install, not working immediately after.

I've examined the network traffic, and the live playback sequence of events looks correct - the browser requests a URL for playback, gets a 401 response, repeats the request with the right credentials, and gets a 200 response, after which the video data begins streaming.  The problem is that the plugin is not handling the incoming video data, and only for live views.

I've tried disabling every feature I can find in the Bitdefender interface, to figure out where the problem is (which itself is a huge UI failure on the part of this program - there should be a single control to suspend all protection for a period of time or indefinitely).  No change.  Even with everything disabled, when the browser prompts for whether or not to let the plugin continue, pressing the Continue button causes the Bitdefender window to flash in the taskbar, indicating that it's still doing something to interfere.

How do I go about figuring out which component is breaking my security camera functionality, so I can add the required exception?